Pneumatic recuperator for a gun



June 19, 1956 v F. LUCHT PNEUMATIC RECUPERATOR FOR A GUN `2 sheets-sheet 1 Filed May 17, 1951 June 19, 1956 V, F, LUCHT 2,750,847

FNEUMATIC RECUPERATOR FOR A GUN Filed May 17, 1951 2 Sheets-Sheet 2 INVENTOR. 'Viffi :rr F'. Lurzh;

arent p 2,750,847 Patented June 19, 1956 PNEUMATIC REcUrEnAroR Fon A GUN Victor F. Lucht, Arlington, Va., assignor to the United States of America as represented by the Secretary of the Army Application May 17, 1951, Serial No. 226,925

7 Claims. (Cl. 89--43) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described in the specification and claims may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

The present invention relates to a new and improved concentric, pneumatic recuperator for guns which operates by means of compressed gas, and wherein the compressed gas is sealed by new and improved oil seals.

The present invention further relates to a new and improved pneumatic reeuperator for guns, wherein pressurized gas is conned to a space between the barrel and the cover surrounding the barrel by means of oil seals, one of which is stationary, while the other is locked to the barrel for movement in unison therewith during recoiland counterrecoil, and wherein the movable oil seal effectively constitutes a piston assembly which 'further compresses the pressurized gas during recoil, and which restores the barrel into battery as a result of the force exerted by the further compressed gas onthe movable oil seal during counterrecoil when the further compressed gas is permitted to expand.

It is accordingly an object of the present invention to provide a new and improved concentric, pneumatic recuperator for guns.

it is a further object of the present invention to provide a pneumatic recuperator which contains gas under pressure for proper and reliable operation thereof.

lt is a still further object of the present invention to provide new and improved oil seals for preventing escape of the gas under pressure from the pneumatic recuperator.

It is another object of the present invention to utilize oil under pressure to increase the effectiveness of the oil seals.

lt is another object of the present invention to provide springs interposed between the oil under pressure and the gas under pressure to improve the efficacy ofthe seals, the springs being compressed by the forces of ythe pressurized gas and oil. v

Other objects and advantages of the presentinvention will become obvious to those skilled in the art from the following detailed description in connection with the accompanying drawings which show for purposes of illustration only one preferred embodiment of the present invention, and wherein:

Fig. 1 is a longitudinal cross-sectional Vview of the pneumatic recuperator in its normal operating position prior to recoil in accordance with the present invention.

Fig. 2 is a fragmentary, longitudinal, cross-sectional view of the front end of the pneumatic recuperator during recoil in accordance with the present invention.

Fig. 3 is a cross-sectional view taken along lines 3-3 in Fig. 1.

Fig. 4 is a cross-sectional view taken along lines 4 4 in Fig. 1.

Fig. 5 is an enlarged, fragmentary, longitudinal, crosssectional view of a portion of the front end of the pneumatic recuperator, and

Fig. 6 is a perspective broken view of the guide sleeve forming a component part of the invention.

Referring now more particularly to the drawings wherein like reference numerals designate like elements in the various figures, reference numeral 1 designates the gun barrel. A cover or tube 2 is coaxial with and surrounds barrel 1 to dene an annular chamber 30 therebetween. Four quadrantal bosses 3 and four quadrantal bosses 3 of the same maximum diameter are rigidly aiiixed to barrel 1 in any conventional manner as by Welding or the like, or may be formed therewith as an integral part of the barrel during its manufacture. The spacing between bosses 3 and 3 defines a circular groove or channel 4 which receives key or segment ring 5 as will be described more fully later on. Moreover the bosses 3 and 3 each of which extends over an arc less than 90, are positioned in such a manner as to conjointly deiine four axially-extending spline grooves 4 which permit ready assembly of the front end of the pneumatic recuperator as will be explained hereinafter. A guide sleeve 6 having an internal diameter slightly larger than the maximum outside diameter of bosses 3 and 3 is mounted over the bosses. The guide 6 has four arcuate splines 6 (Fig. 6) as shown in Fig. 4, protruding internally from its rearward portion. Splines 6 are of such dimension and spaced in such a manner as to slidably fit grooves 4 thereby preventing relative rotation between the barrel and guide or sleeve. Key 5 consists of two separate, semi-circular steel rings which are so dimensioned as to t into groove 4 ush with the contiguous surfaces of bosses 3 and 3. In the assembly of the front end of the pneumatic recuperator, guide sleeve 6 is moved over bosses 3 and 3 toward the left (as viewed in Fig. 1) until groove 4 is uncovered, whereupon the two semi-circular portions of key S are placed in position in groove 4. Sleeve 6 is then returned toward the right (as viewed in Fig. l) until splines 6 engage the portions of key 5 extending across grooves 4'. Guide 6 is provided with an internal thread 7 and an external thread S. A nut 9 having an external thread engages the internal thread 7 of guide 6. Nut 9 is also provided with an internally tapered end portion having a similar angle of inclination as the taper of bosses 3 whereby nut 9 locks sleeve 6 to the barrel. It is thus seen that sleeve 6 is rigidly held in place with respect to bosses 3 and 3 and barrel 1 by means of key 5 and nut 9. Another sleeve 10` having an interntl thread which engages the external thread 8 of guide 6 serves as a seal for the front end of the pneumatic recuperator, and retains in position rings 11, 12 and packing 13, which are located between nuts 9 and an internal llange on the forward end of sleeve 1t), and which provide an effective seal between sleeve 10 and barrel 1. In one embodiment packing 13 was made of synthetic rubber. Sleeve 10 is also provided with coaxial bores 14 and 15 into which the valve assembly 16 is threaded. Valve 16 comprises a ball 1/ and pin 13 as is conventional with ball valves. Sleeve 10 further comprises a peripheral groove or recess 18 which receives packing 19 thereby effectively sealing the space between cover 2 and sleeve 10. The peripheral surfaces 10' of sleeve 10 are built up or plated with anti-friction material to minimize wear thereof during recoil and counterrecoil. A helical spring 20 is retained between spacer 21 and retainer ring 22. Retainer ring 22 is provided with two peripheral grooves 23 and 24 which receive packings 25 and 26 respectively, thereby effectively providing a seal between tube 2 and retainer ring or piston 22 on the one hand, and between retainer ring 22 and sleeve 10 on the other. Snap ring 27 is seated in a small recess provided for such purposes in the external rear surface of sleeve 10; shoulder 21 of spacer 21 rests 3 against the protruding portion of snap ring 27, spacer 21 being urged toward the left (as viewed in Figures l and by the force of spring 20. A small bore 28 provides an interconnecting passageway between annular chamber 29 and the valve assembly 16, so that oil may be supplied under pressure to the chamber. The oil under pressure exerts a force against piston 22 of retainer ring 22.

and is confined to space 29 by packings 19, 25, and 26. The peripheral surfaces 22" of retainer ring 22 are built up with anti-friction material similar to surfaces 1li of nut 1G to prevent excessive wear thereof during recoil and counterrecoil. The maximum diametrical dimension of spacer 21 is sufficiently smaller than the inside diameter of cover 2 to permit free passage for the gas under pressure from space 39 into the space occupied by spring 20. A wiper ring 31, which may be made of felt, is positioned in the peripheral groove provided therefor in retainer ring 22, and serves to wipe the inner surface of cover 2 during recoil and counterrecoil. Gas under pressure, such as nitrogen, is supplied to space 30 through pressure regulator valve 32.

The rear end of the pneumatic recuperator is housed in part in the rear end of cover 2 and in part in the front end of cradle 33; the rear end of cover 2 is provided with an externally threaded portion 34 which engages an internally threaded portion in the front endV of cradle 33 whereby cover 2 is rigidly attached to cradle 33. A retainer ring 35 rests against shoulder 36 in cradle 33, and is secured in that position by nut 37, the external thread 3S of which engages a corresponding thread provided on the inner surface of cradle 33. Six equally spaced, threaded holes 35 in retainer ring 35 are utilized for extraction of the retainer ring from its assembled position in cradle 33 as the screws, which are inserted therein at that time, will provide a readily accessible and safe means to which the extracting force may be applied without damage to the retainer ring 35 itself. Gasket 39 and packing are mounted in peripheral grooves 41 and 42 provided therefor in retainer ring 35. Packing 40 provides an effective seal between retainer ring 35 and barrel 1, while gasket 39 provides an effective seal between retainer ring 35 and cradle 33. Four equally spaced splined slots 37 in the nut 37 permit the use of a four pronged tool or spanner for tightening or extracting nut 37 in the assembly and disassembly of the pneumatic recuperator. The external thread 43 of ring or nut 44 engages a corresponding thread on the inside surface of cover 2 whereby the abutment of ring 44 rests against shoulder 45 of cover 2. Ring 44 is provided with four equally spaced spline slots 44 similar to spline slots 37 in nut 37, whereby the same four-pronged tool may be used for tightening or extracting nut 37. A helical spring 46 is retained between spacer 47 and an internal circular shoulder formed at the front end portion 48 of follower or guide 49. Spacer 47 is forced by spring 46 against rearwardly-facing shoulder 58 in cover 2. The front portion 48 of follower 49 retains packing 50 in peripheral groove 51 whereby an effective seal is established between follower 49 and cover 2. The rear portion 48 houses packing 52 and wiper 53 in respective peripheral grooves 54 and 55. Packing 52 provides an effective seal between follower 49 and barrel 1 while wiper 53 acts on the external surface of barrel 1 during recoil and counterrecoil. A supporting flange 54 extends radially from the frusto-conical portion of follower 49 connecting front portion 48 with rear portion 4S. Rear portion 48' and ange 54 are each provided with twelve, equally-spaced, aligned holes 55 and 55 respectively which permit passage of the oil to the rearward areas of the rear oil seal of the pneumatic recuperator. Cover 2 is further provided with a ball valve 56, Figure l, similar in structure and purpose to valve 16. A gasket 57 provides a seal between cover 2 and cradle 33.

In the operation of the pneumatic recuperator, oil under pressure is supplied to the front oil seal through valve 16 and to the rear oil seal through valve 56. In actual practice in one embodiment Van oil pressure of fty pounds per square inch was used. The oil in the front seal is confined by packings 19, 25 and 26 to a space defined by sleeve 10, cover 2, and retainer ring 22; the oil in the rear seal is confined by packings 39, 49, 52, 57, to a space defined by follower 49, barrel 1, retainer ring 35, cradle 33 and cover 2. Next a gas, such as nitrogen, is supplied under pressure to space 30 by means of valve 32; in one embodiment a gas pressure of sixty pounds per square inch was used successfully. Packings 19, 25, 26 and 13, and the oil in space 29 prevent any leak of the pressurized gas through the front seal of the pneumatic recuperator, while packings 50 and 52, and the oil in the rear seal prevent any leak of the pressurized gas therethrough. Spring 46 and the gas pressure exert sufficient force on follower 49 so that the follower assembly 48, 48', 49 and 54 will move toward the left (as viewed in Fig. l) until flange 54 rests against ring nut 44. Spacer 47, spring 46 and follower 49 may thus be assembled in cover 2 and kept in position by means of nut 44 prior to the assembly of cover 2 in cradle 33. Sufficient play is provided between the outside diameter of front portion 48 and flange 54, and the inside diameter of nut 37 to permit free travel of follower 49 over its limited range defined by nut 44 and spacer 47 when the movement of barrel 1, which moves inside follower 49, will tend to impart similar movement to the follower 49 through the friction offered by packing 52.

The pneumatic recuperator is shown in its normal position in Fig. l prior to recoil. During recoil the entire front seal consisting of guide 6, key 5, nuts 9 and 10, rings 11 and 12, spacer 21 and retainer ring 22 together with spring 20, packings 13, 19, 25, and 26, and snap ring 27 is moved in unison with barrel 1 toward the left (as viewed in Fig. l) to the position shown upon Figure 2. As pointed out above, guide 6 is locked to barrel 1 by means of bosses 3 and 3', key 5 and nut 9; sleeve 10 threadably engages guide 6, while retainer ring 22 sldably engages nut 10, and spacer 21 is locked to nut 10 by means of snap ring 27 whereby the front seal assembly is locked to barrel 1. The front seal assembly constitutes effectively a piston assembly for the gas under pressure in space 30, and thus further compresses the gas in space 30 during recoil, since the gas is confined at all times to space 30 by the front and rear seal assemblies which prevent any leak or escape of the gas. Upon termination of the recoil, the compressed gas will act on the front seal assembly in the same manner as a compressed gas acts on and moves a piston assembly, thereby initiating the counterrecoil and restoring barrel 1 together with the front seal into battery as shown in Fig. 1. A stop forming no part of the present invention is provided in the breech end of the gun which limits the movement of the barrel and of the front seal assembly during counterrecoil to a point where the front seal assembly is at all times surrounded by cover 2.

It is thus seen that the pneumatic recuperator in accordance with the present invention may be easily assembled and disassembled, which greatly facilitates replacement of worn parts. Moreover the cost of manufacture of the individual parts of the pneumatic recuperator is relatively small in comparison with prior art devices and adapts itself readily to standardization of these parts. Furthermore the pneumatic recuperator in accordance with the present invention is simple in construction without sacrifice to reliability of operation.

While I have shown and described only one preferred embodiment of my invention it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and l desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or Vas are specifically set forth in the appended claims.

I claim:

1. A pneumatic recuperator for guns operative in response to compressed gas confined to a space between the barrel and the cover by means of a stationary and a movable sealing means, said cover being secured at its rear end to the cradle of the gun, said stationary sealing means being located in the rear end of said cover and comprising a first retainer ring, a first nut for securing said first retainer ring against a shoulder in said cradle, a follower having a rear portion, a front portion, and a slanting portion connecting said rear portion to said front portion, said slanting portion including a fiange portion, said rear portion and flange portion being provided with a plurality of aligned holes to permit passage of the sealing fluid to the rearward areas of said stationary sealing means, a second nut limiting the movement of said follower in one direction, a rst spacer and a helical spring, said spring being interposed between said front portion and said first spacer thereby limiting the movement of said follower in the opposite direction, a pressure valve in said cover, and packings mounted in said first retainer ring, in said rear portion and in said front portion; said barrel having quadrantal bosses defining a circular groove and four aligned spline grooves; said movable sealing means being located in the front end of said cover and comprising a guide mounted over said bosses, said guide having four arcuate splines in slidable relation to said spline grooves, a key mounted in said circular groove for locking said guide to said barrel for movement therewith in one direction, a third nut threadably engaging said guide for locking said guide to said barrel for movement therewith in the opposite direction, a fourth nut mounted over said third nut threadably engaging said guide, said fourth nut including a pressure valve, a second retainer ring and a second spacer fastened to said fourth nut, a helical spring interposed between said second retainer ring and said second spacer, and packings mounted in said second retainer ring, in said lfourth nut, and in the space between the third and fourth nut; and means for supplying gas under pressure to the space between said cover and said barrel intermediate said two sealing means.

2. In a pneumatic recuperator for a gun, a barrel having a cylindrical exterior surface, a cradle mounting the breach end f said barrel for axial recoil and counterrecoil, a tube fixed with said cradle at its rearward end and extending forwardly along and about said barrel with its cylindrical interior surface coaxial with and radially spaced from said barrel, a rst pressure seal fixed with said barrel at the forward end of said tube and slidably fitting the same, a second pressure seal fixed with said tube at the rearward end of the latter and slidably fitting about said barrel, each said seal comprising means forming respective discrete annular sealed chambers extending about said barrel, a body of oil filling each said chamber, means including a spring to exert a force upon each said body of oil respectively, to maintain the same under initial pressure, and a body of gas under initial pressure within the chamber formed by said barrel, tube and pressure seals.

3. ln a pneumatic recuperator for a gun, a barrel having a cylindrical external surface, a cradle mounting said barrel at the breech end thereof for axial reciprocation in recoil and counterrecoil, a tube rigidly secured at its rear end to said cradle and extending forwardly along and about said barrel coaxially therewith to define with said barrel an annular chamber therebetween, a sleeve rigidly secured to said barrel in pressure-tight relation therewith and having a cylindrical portion extending rearwardly between said barrel and tube in spaced coaxial relation with each, said sleeve having a forward enlargement slidably fitting said tube, sealing ring means connected with said sleeve and between said sleeve and tube, said means defining with said sleeve, tube and enlargement, an annular liquid-tight pressure chamber, said sleeve and said sealing ring means recoiling as a unit with the barrel, and oil seal means between said barrel and tube contiguous with said cradle and substantially fixed with said tube, whereby a pressure-tight chamber is formed between said barrel and tube of diminishing volume in response to recoil.

4. In a pneumatic reciprocator for a gun, a barrel having a cylindrical exterior surface, cradle means mounting said barrel at the breech end thereof for axial reciprocation, a tube fixed at one end with said cradle means and extending forwardly along and about said barrel with its interior cylindrical surface coaxial, and defining an annular gas chamber, with said barrel, a sleeve having a forward enlargement slidably fitting said tube in fluidtight relation therewith and a rearwardly-extending portion between said barrel and tube in radially spaced relation therewith, means rigidly and removably connecting said sleeve .and barrel contiguous the forward end of said sleeve and forming a gas-tight seal with said barrel, a spacer ring about said sleeve adjacent the rearward end thereof, a retainer ring slidable on and along said sleeve forwardly of said spacer ring and forming a uid seal between said sleeve and tube, a coil spring about said sleeve between said rings and urging the same apart, abutment means limiting rearward movement of said spacer ring relatively to said sleeve, a liquid under pressure filling the space between said sleeve, tube, enlargement and retainer ring, means fixed with said cradle means and tube at the rearward end of said tube and forming a gas tight seal between said tube and barrel, and valve means in said tube for introducing a gas under pressure into said gas chamber.

5. In a pneumatic recuperator for a gun, a barrel having a cylindrical exterior surface, a cradle mounting the breech end of said barrel for axial reciprocation, a tube secured at its rearward end to said cradle and extending forwardly along and about said barrel with its cylindrical interior surface in radially spaced coaxial relation therewith, first gas tight sealing means fixed with said barrel and slidably fitting the forward end of said tube, second gas tight sealing means fixed with said tube rearwardly of said first sealing means and slidably fitting about said barrel, said barrel, tube and sealing means forming an annular gas-tight chamber, gas under pressure in said chamber, said first sealing means comprising a sleeve having a piston enlargement slidably fitting said tube, gas-tight means fixing said sleeve to and about said barrel at the forward end of said tube, a spacer ring mounted about the rearward end of said sleeve, a retainer ring slidably fitting about and between said sleeve and tube forwardly of said spacer ring, sealing means carried by said retainer ling between said sleeve and tube, spring means between said rings and urging the same apart, labutment means between said sleeve and spacer ring and limiting rearward movement of said spacer ring relatively to said sleeve, sealing means between said enlargement and tube, land a liquid under pressure between said enlargement and retainer ring.

6. In a pneumatic recuperator for a gun, a barrel having a cylindrical exterior surface, a cradle mounting the breech end of said barrel for axial reciprocation, a tube secured at its rearward end to said cradle and extending forwardly along and about said barrel with its cylindrical interior surface in radially spaced coaxial relation therewith, first gas tight sealing means fixed with said barrel and slidably fitting the forward end of said tube, second gas tight sealing means fixed with said tube rearwardly of said first sealing means and slidably fitting about said barrel, said barrel, tube and sealing means forming an annular gas-tight chamber, a gas under pressure in said chamber, said second sealing means comprising a first ring xed with said tube in duid-tight relation therewith and extending about said barrel, sealing means between said ring and barrel, a second ring slidably iitting Within said tube forwardly of said first ring and having a rearwardly extending portion slidably receiving said barrel, sealing means between said second ring and tube and between said second ring and barrel, a spacer ring slidable within said tube forwardly of said second ring, abutment means between said tube and spacer ring limiting forward movement of the latter, spring means between said second ring and said spacer ring urging them apart, and a liquid under pressure in the space defined by said barrel, tube, irst and second rings.

7. In a pneumatic recuperator, a barrel having a cylindrical external surface, a cradle surrounding and mounting said barrel for reeiprocation in recoil and counterrecoil, a tube having a smooth unbroken interior surface along its forward portion thereof rigidly secured at its rear end only to said cradle and extending forwardly along said barrel coaxially therewith to define an annular chamber between said tube and said barrel, a sleeve, means lixedly securing said sleeve to said barrel within and at the forward end 0f said tube coaxially therewith, said sleeve having a. forward cylindrical enlargement slidably fitting said tube, a first gas-tight oil sealing means fixed to said barrel to move as a unit therewith entirely within the smooth forward portion of said tube, said first sealing means delining with said enlargement an annular oil pressure chamber acting as a pressure seal between said tube and said sleeve, and a second gas-tight sealing means disposed in the rearward portion of said tube, said second sealing means defining an annular oil pressure chamber and acting as a pressure seal between said barrel and said tube, and a body of gas under ini tial pressure within said annular chamber formed by said barrel, tube and said sealing means, the volume of said chamber decreasing in response to recoil of said barrel within said tube.

References Cited in the tile of this patent UNITED STATES PATENTS 1,719,597 Dawson et al. July 2, 1929 2,088,592 Gurney Aug. 3, 1937 2,339,227 Trotter Jan. 11, 1944 2,395,488 Lucht Feb. 26, 1946 2,442,371 Meyers et al. .Tune 1, 1948 2,454,818 Lucht Nov. 30, 1948 

